I inherited a database and in order to keep from rebuilding it I want to
change the way a value is populated in a form field.

Basically, the form has an order ID (autonumber) and an order number (text
with number)  I want to change the order number to a pure number and then
have it figure what number should be next and auto populate it.  I thought of
just coping the autonumber value, but having it figure the next number may be
easier.  

What would the module command look like?

I have this in another database:
****************************
Option Compare Database

Public Function NextOrderNo() As String

  Dim db As DAO.Database
  Dim rs As DAO.Recordset

  Dim strSQL As String

  strSQL = "SELECT Max(CLng(Mid([Ticket # :], 4))) " & _
           "FROM [Routing Details - Table]"

  Set db = CurrentDb
  Set rs = db.OpenRecordset(strSQL, dbOpenSnapshot)

  NextOrderNo = "MCO" & rs.Fields.Item(0).Value + 1

  rs.Close
  Set rs = Nothing
  Set db = Nothing

End Function

I hate to mess with what is working, but I am getting complaints about the
text & number field not sorting using the digits as numbers.  Ex: MCO1,
MCO11, MCO111, MCO2, MCO3 etc…